N-(beta-diorganodithiophosphorylethyl) aryl and alkyl sulfonamides are known for their utility in agricultural applications. For example, U.S. Pat. No. 3,205,253 discloses certain types of these compounds as selective herbicides, and U.S. Pat. No. 3,368,001 discloses other types of these compounds as insecticides and fungicides.
Each of the above-mentioned patents teaches the preparation of the sulfonamides disclosed therein by reaction of a N-(beta-haloalkyl)-aryl or -alkyl sulfonamide with a salt of the appropriate phosphorus compound, such as ammonium diethyldithiophoshate. U.S. Pat. No. 3,415,909 discloses an improvement in the process, whereby the same reaction is carried out at a pH in excess of about 9.5. The N-(beta-haloalkyl)-aryl or -alkyl sulfonamide in these processes is a compound which is prepared by a series of complex batch-wise operations, including a necessary dehydration at several points in the procedure.
Some of these problems were avoided by the discovery of a process involving substituted-sulfonyl ethyleneimines. This process is described in U.S. Pat. No. 3,392,215. The ethyleneimines were reacted directly with a dithiophosphoric acid rather than the acid salt.
It has now been discovered that the use of ethyleneimines can be avoided, as well as the complexity inherent in the preparation of N-(beta-haloalkyl)-aryl or -alkyl sulfonamides. This discovery entails a novel process for the manufacture of N-(beta-diorganodithiophosphorylethyl) aryl and alkyl sulfonamides. This novel process is the process of the present invention, and is fully described hereinbelow.